Experimental study on the liquid hydrogen zero boil-off in a liquefaction system with an automatic control technology

Abstract

In this study, an automatic control technology for liquid-hydrogen zero boil-off was developed to improve the long-term storage capability of small-scale liquefaction systems. An innovative system capable of monitoring both the pressure within the heat pipe and the pressure within the LH 2 vessel was developed. This innovative approach ensures continuous efficiency and reduces downtime, significantly improving the overall performance of the hydrogen liquefaction process. The optimal conditions for automatic control were obtained through a cycle test in ON/OFF mode. In addition, experimental investigations were conducted sequentially to investigate the effect of the water level of liquid hydrogen such as 1st section, 2nd section and 3rd section of LH 2 . As a result, these experiments successfully demonstrated zero boil-off of liquid hydrogen for long-term storage in the vessel, corresponding to a constant value in the liquid level meter in each section. The velocity of stabilization from the temperature and pressure perspectives in the vessel increased, and the entire cryocooler cycle time was significantly influenced by the amount of liquid hydrogen produced. • An automatic control technology for liquid-hydrogen zero boil-off was developed. • The pressure data on the liquid hydrogen vessel and heat exchanger were determined. • The effect of the water level of liquid hydrogen was investigated. • Experiments demonstrated zero boil-off of liquid hydrogen for long-term storage. • The entire cryocooler cycle time was influenced by the amount of liquid hydrogen.